Electric actuator for motor vehicles

Abstract

An electric actuator (10) for motor vehicles, comprising a first transmission element (18) associated with a drive shaft (16) of a reversible drive motor (14) and a second transmission element (24) associated with an output shaft (22), and a third transmission element (28) arranged between the first transmission element (18) and the second transmission element (24), wherein the first and third transmission elements (18, 28) and the second and third transmission elements (24, 28) are each operatively connected to one another, and wherein the first, second, and third transmission elements (18, 24, 28) each have at least one functional area for the operative connection, characterized in that one of the transmission elements (18, 24, 28) has at least one end stop (30, 32) for limiting the rotational mobility of the output shaft (22), wherein the end stop (30, 32) is located in the area of ​​one of the functional areas, wherein the Functional area with end stop (30,32) is formed from teeth of a gear (26) and the end stop (30, 32) is formed by a flank of the associated tooth (37, 38) that is widened and correspondingly flattened in the circumferential direction of the gear (26).

Description

[0001] The invention relates to an electric actuator for motor vehicles with a first gear means assigned to a drive shaft of a reversible drive motor and a second gear means assigned to an output shaft, and with a third gear means arranged between the first gear means and the second gear means, wherein the first and third gear means and the second and third gear means are each operatively connected to one another, and wherein the first, second and third gear means each have at least one functional area for the operative connection.

[0002] Such actuators are used in motor vehicles, for example, for electrically operated seat adjustments. DE 101 15 151 A1 discloses an electric actuator in which the rotary motion of a drive motor's input shaft is transmitted to an output shaft. A multi-stage gear arrangement with several spur gears and a worm gear is provided to adapt the force and torque curves to the requirements of the output shaft. The rotary motion of the output shaft is limited to an angular range of less than 180°. Separate stops and spring elements are provided for the resulting end positions.

[0003] DE 101 15 636 B4 and DE 42 38 368 A1 describe gear arrangements in which end stops are formed by elastic elements attached to the housing.

[0004] The disadvantage of defining end positions using separate stops and spring elements is that these must be handled as separate components during actuator assembly, thus increasing assembly effort. Furthermore, due to the additional components, they increase the manufacturing costs of an actuator.

[0005] The invention is based on the object of developing an actuator of the type mentioned at the outset in such a way that it has defined end stops, whereby the number of components to be manufactured and handled should be as small as possible.

[0006] To achieve this objective, one of the gearing means is provided with at least one end stop for limiting the rotational mobility of the output shaft, wherein the end stop is located in the region of one of the functional areas. This simplifies the handling of the individual parts during the assembly process of the individual components of the actuator, thereby reducing both assembly times and manufacturing costs.

[0007] In a further development of the invention, the rotational mobility of the output shaft is limited to a range of up to 355°. This allows the maximum possible rotational range of just under 360° to be almost fully utilized.

[0008] In a further embodiment of the invention, the end stop is located on the second gearing means. This places it as close as possible to the output shaft, which in turn allows the maximum possible rotation range of just under 360° to be achieved.

[0009] In a further development of the invention, the first, second, and third gearing means form a gear transmission, with the functional areas being formed by the respective teeth. By choosing a gear transmission with straight teeth, the individual gearing means can be manufactured relatively cost-effectively.

[0010] In a further embodiment of the invention, the second and third gearing means are designed as spur gears, and the first gearing means is designed as a worm or spur gear. The worm, in combination with the spur gears, ensures a high transmission ratio. Furthermore, the use of a worm allows the gearing to be self-locking if necessary.

[0011] In a further embodiment of the invention, the third gearing means consists of a plurality of meshing spur gears. By arranging any number of gears between the first gearing means and the second gearing means, the gear ratio can be further varied as required.

[0012] In a further development of the invention, the lateral additional flanks have a receiving recess for a tooth of another, operatively connected gear. This allows the stresses that arise in the tooth of the mating gear engaging in the recess to be reduced by the uniform surface contact.

[0013] In a further embodiment of the invention, the additional flanks are integrally connected to the second gearing means. This further reduces the number of components to be handled during assembly.

[0014] In a further development of the invention, the second and third transmission means are designed as a single component. This allows the number of components to be further reduced.

[0015] The invention is explained in more detail using the following exemplary embodiment. It shows: Fig. 1 A top view of an opened electric actuator; Fig. 2 a detailed view A of the actuator according to Fig. 1.

[0016] In Fig. 1 shows an open electric actuator 10, wherein the housing half is not shown and the lower housing half 12 accommodates a drive motor 14. The drive motor 14 has a drive shaft 16, to which a first gear means 18 in the form of a worm 20 is attached. Furthermore, the actuator 10 has an output shaft 22, which is perpendicular to the plane of the page in the illustration according to Fig. 1 and serves for connection to a component to be actuated by the actuator 10. A second gear 24 in the form of a spur gear 26 on the output shaft side is assigned to the output shaft 22. A third gear 28 in the form of a multi-stage spur gear arrangement consisting of a plurality of meshing spur gears is arranged between the worm 20 and the output shaft-side spur gear 26. All gears are operatively connected to one another in such a way that a rotational movement of the drive shaft 16 on the output shaft 22 causes a corresponding rotational movement, whereby the speed and the available torque can vary depending on the transmission ratio of the spur gear arrangement.

[0017] The actuator 10 is designed such that the spur gear 26 on the output shaft can rotate through an angle of just under 360°. To ensure end limitation, as shown in Fig.2, a first end stop 30 and a second end stop 32 are provided. The first and second end stops 30, 32 are positioned in the area of ​​the gear ring 34 of the output shaft-side spur gear 26, which can also be referred to as the functional area.

[0018] The second end stop 32 is located in the area of ​​the tooth flank 36 of the tooth 38 and is designed to increase the thickness of the tooth 38 on one side in this area. To more evenly accommodate the engaging tooth 40, the tooth 38 has a receiving recess 42. This receiving recess 42 is designed to correspond to the contour of the tooth 40 and ensures uniform surface pressure, as the tooth engages the receiving recess.

[0019] During operation of the actuator, the spur gear 26 on the output shaft side can only be moved within a range defined by the two end stops 30, 32, corresponding to a rotation range of slightly less than 360°. Due to the reversibility of the direction of rotation of the drive motor 14, the output shaft 22 can be moved in any direction depending on the positioning requirements of the components to be moved. If the output shaft 22 approaches the end stops, over-rotation is reliably prevented.

Claims

[1] Electric actuator (10) for motor vehicles with a first gear means (18) assigned to a drive shaft (16) of a reversible drive motor (14) and a second gear means (24) assigned to an output shaft (22), and with a third gear means (28) arranged between the first gear means (18) and the second gear means (24), wherein the first and third gear means (18, 28) and the second and third gear means (24, 28) are each operatively connected to one another and wherein the first, second and third gear means (18, 24, 28) each have at least one functional area for the operative connection, characterized bythat one of the gear means (18, 24, 28) has at least one end stop (30, 32) for limiting the rotational mobility of the output shaft (22), wherein the end stop (30, 32) is located in the region of one of the functional areas, wherein the functional area with the end stop (30, 32) is formed from teeth of a gear wheel (26) and the end stop (30, 32) is formed by a flank of the associated tooth (37, 38) which is widened in the circumferential direction of the gear wheel (26) and correspondingly flattened. [2] Electric actuator according to claim 1, characterized by that the limitation of the rotational mobility of the output shaft (22) is restricted to a range of up to 355°. [3] Electric actuator according to claim 1 or 2, characterized by that the end stop (30, 32) is located on the second gear means (24). [4] Electric actuator according to one of the preceding claims, characterized bythat the first, second and third gear means (18, 24, 28) form a gear transmission and the functional areas are formed by the respective teeth. [5] Electric actuator according to one of the preceding claims, characterized by that the second and third gear means (24, 28) are designed as spur gears. [6] Electric actuator according to one of the preceding claims, characterized by that the lateral additional flanks have a receiving recess (42) for a tooth of another operatively connected gear. [7] Electric actuator according to one of the preceding claims, characterized by that the second and third transmission means (24, 28) are designed as one component.

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